Basket type treatment tool

Abstract

A basket type treatment tool includes a sheath, a distal end cover attached to a distal end of the sheath and having grooves including first and second grooves, basket wires, and an operating wire, the first groove has first surface in which at least part of bottom surface of the first groove is inclined in a direction along the basket wires that are in a state in which the basket protrudes from the distal end cover, the second groove has second surface in which at least part of bottom surface of the second groove is inclined in a direction along the basket wires, and when the operating wire is pulled through a different one of the plurality of groove sections and abuts one of the first surface and one of the second surface.

What is claimed is: 
     
       1. A basket type treatment tool comprising:
 a sheath extending in a longitudinal axis direction; 
 a distal end cover that is cylindrical and attached to a distal end of the sheath, the distal end cover including a plurality of grooves extending from an inner circumferential surface to an outer circumferential surface of the distal end cover, the grooves being concave; 
 a plurality of basket wires that are configured to extend and retract from the distal end cover and configured to form a basket, the basket being configured to expand and contract according to extension and retraction from the distal end cover; and 
 an operating wire connected to proximal ends of the plurality of basket wires and configured to advance from and retract into the sheath, wherein:
 the plurality of grooves includes a first groove and a second groove separate from the first groove in a circumferential direction of the distal end cover, 
 the first groove has a first surface, the first surface having a first chamfering amount, 
 the second groove has a second surface, the second surface having a second chamfering amount that is smaller than the first chamfering amount. 
 
 
     
     
       2. The basket type treatment tool according to  claim 1 , wherein among the plurality of basket wires, a basket wire in contact with the second surface is configured to break before a basket wire in contact with the first surface. 
     
     
       3. The basket type treatment tool according to  claim 2 , wherein the second chamfering amount is half of the first chamfering amount. 
     
     
       4. The basket treatment tool according to  claim 2 , wherein the second chamfering amount is less than half of the first chamfering amount. 
     
     
       5. The basket type treatment tool according to  claim 1 , wherein: the plurality of grooves includes at least two second grooves; and the second grooves neighbor each other in the circumferential direction. 
     
     
       6. The basket type treatment tool according to  claim 1 , wherein a number of the grooves is equal to a number of the basket wires. 
     
     
       7. The basket type treatment tool according to  claim 1 , wherein the first surface and the second surface are inclined from bottom surfaces of the first groove toward an inner circumferential surface of the distal end cover in a longitudinal axis direction of the distal end cover. 
     
     
       8. The basket type treatment tool according to  claim 7 , wherein: the second surface is chamfered such that a bottom surface of the second groove has a dimension different from the first surface. 
     
     
       9. The basket type treatment tool according to  claim 1 , wherein: when the operating wire is pulled in a direction from the distal end toward the proximal end of the sheath in a state in which a treatment object is accommodated in the basket, each of the plurality of basket wires is pulled through a different one of the plurality of groove sections, and a breaking force of one of the basket wires abutting on the first surface is different from one of the basket wires abutting on the second surface. 
     
     
       10. The basket type treatment tool according to  claim 1 , wherein when the operating wire is pulled from the distal end toward the proximal end of the sheath, each of the plurality of basket wires is pulled through a different one of the plurality of grooves and abuts one of the first surface and one of the second surface. 
     
     
       11. The basket treatment tool according to  claim 1 , wherein a portion of the second surface of the second groove has an inclination or a length different from the first surface. 
     
     
       12. The basket treatment tool according to  claim 1 , wherein the first surface that is inclined in a same direction as an incline of a portion of the basket wires when the basket protrudes from the distal end cover. 
     
     
       13. The basket treatment tool according to  claim 1 , wherein the second surface that inclined in a same direction as an incline of a portion of the basket wires when the basket protrudes from the distal end cover. 
     
     
       14. A basket type treatment tool comprising:
 a sheath extending in a longitudinal axis direction; 
 a distal end cover that is cylindrical and configured to connect to a distal end of the sheath, the distal end cover including a plurality of grooves extending from an inner circumferential surface to an outer circumferential surface; 
 a plurality of basket wires that are configured to extend and retract from the distal end cover and configured to form a basket, the basket being configured to expand and contract according to extension and retraction from the distal end cover; and, 
 an operating wire connected to proximal ends of the plurality of basket wires and configured to advance from and retract into the sheath, wherein:
 the plurality of grooves includes a first groove and a second groove separate from the first groove in a circumferential direction of the distal end cover, 
 the first groove has a first surface that is aligned with a portion of the basket wires when the basket protrudes from the distal end cover, 
 the second groove has a second surface that is aligned with a portion of the basket wires when the basket protrudes from the distal end cover, 
 the first surface and the second surface are provided in a same corresponding position in the first groove and the second groove, respectively, and 
 a portion of the second surface of the second groove has an inclination or a length that is different from the first surface.